Marion Nestle, PhD, MPH, is one of America’s best-known critics of food safety and nutrition. The author of Food Politics and What to Eat as well as a popular columnist and blogger, she is the Paulette Goddard professor of nutrition, food studies and public health at New York University. In 2007, she and her partner, Malden Nesheim, PhD, professor and provost emeritus of Cornell University—both of whom are Bark contributing editors—turned their attention to the pet food industry. The result is Nestle’s book, Pet Food Politics: The Chihuahua in the Coal Mine, the story of the melamine pet food recalls, and the book they wrote together, Feed Your Pet Right, due out next year. Christie Keith recently spoke with Nestle and Nesheim to find out what they’ve learned about pet food during the last two years, as well as what they see as the relationship between pet and human food safety and nutrition.

BARK: Marion, you’ve frequently said that everyone, whether they have pets or not, should care about pet food because “there is only one food supply.” I think that’s counterintuitive for some people. Could you elaborate?

Marion Nestle: Pets eat the same foods we do—they may eat different parts, but the sources are the same. The pet food recalls were a perfect example of what’s gone wrong with our food system. They made it obvious that food for pets and food for people are inseparable. Taking it a step further, the pet food recalls made the discovery of melamine in Chinese infant formula completely predictable.

BARK: At the time of the recalls, we talked about how few manufacturers (of both pet and human foods) realized that many of their ingredients were coming from a single source, and that many consumers were surprised to find out so many foods were made by the same company (Menu). Did that surprise you, too?

Nestle: We were stunned. We had no idea that a company we had never heard of made 95 brands of pet foods for most of the major companies. And the fact that all those brands—from Ol’ Roy to Iams—were made at one plant? What a revelation. But look how it prepared us for this year’s peanut butter recall, which is the same situation all over again: One company makes an ingredient that goes into thousands of products. The companies making these products have no clue where their peanut butter comes from because they get it from a broker. That’s our food system.

BARK: I was surprised to hear that you’ve come to believe commercial foods are not as bad as you thought they were going to be—that most animals “do fine” on commercial diets. And yet, the American Veterinary Dental Society says 80 percent of dogs and 70 percent of cats show signs of oral disease by the age of three. It’s estimated that something like one in five adult dogs (double that for senior dogs) has arthritis, and there’s a high rate of obesity in dogs and cats. So I wonder if it’s really defensible to say that most dogs in America “do fine.”

Malden Nesheim: One problem is that we don’t have anything to compare to what’s happening now. We found data on the average age of dogs coming to veterinary practices; generally speaking, they are getting older. But what does that mean? Does that mean the dogs are living longer, or that more people are taking animals to veterinarians? We just don’t know.

Nestle: And it’s not for lack of trying. We tried really, really hard to find the kind of statistical information we needed to make a good judgment about trends in pet health, but we couldn’t. We have no idea whether oral disease is getting better or worse and couldn’t even find out whether dogs are living shorter or longer lives now. The data simply don’t exist. And we are dismayed by this.

BARK: So if that’s the case, and we can’t really say with authority that most animals “do fine” on their commercial diet, what advice would you give people trying to decide if the food they’re feeding their dogs is one on which they are thriving?

Nestle: When we say “thrive,” we mean “happy and healthy.” If the animal isn’t thriving on one food or recipe, people should switch to another. If a dog doesn’t like a food, try another one. If a dog develops minor skin or digestive problems, try another food (major problems need veterinary advice along with dietary changes).

BARK: Are the high-end commercial foods—many of which didn’t exist until relatively recently—genuinely superior to lower priced, more mass-marketed products, in objective terms?

Nesheim: We looked for the evidence of such superiority, and of course, couldn’t find much. We were only able to find one published study in which veterinarians compared one commercial diet to another. We’d like to see comparative studies, but who’d fund them? Pet food companies only publish studies that put their products in a good light. All complete-and-balanced products have to meet the same nutritional standards. Only the ingredients vary. Do these make a difference? Maybe, but again, we can’t find the science.

We know dog owners who swear their animals flourish on every kind of diet you can think of, from the cheapest kibble to home-cooked. We think values are at stake here. People have lots of options for feeding their dogs and can choose diets that fit their value systems, lifestyles and pocketbooks. They can do what feels right for them. As long as they are meeting the dog’s nutritional needs—and not underfeeding or overfeeding—the dogs should be okay.

One other thing. We’d like pet food labels to say that the foods were tested in animal feeding studies, as opposed to just meeting the AAFCO profiles. We hear lots of criticisms about feeding studies, that they’re not long enough or don’t use enough animals. But I still feel more comfortable when a food I’m using has been fed to an animal that did okay on it.

Nestle: The testing issue bothered us a lot. Most pet foods aren’t tested on animals to see if they really do meet nutritional needs.

BARK: So, though you say all the foods meet nutritional needs, isn’t it more accurate to say the ones that were tested in feeding trials met the needs of the animals in the feeding trials, according to the parameters of the trials?

Nestle: Yes. The untested pet foods are supposed to have the same nutritional value as the ones actually fed to pets, but we think this is an inferior way of evaluation. We think all complete-and-balanced foods should be tested—we want more testing, not less, and we think the tests should be done under the highest possible standards. In reviewing the literature—how can we put this politely—we were concerned about the quality of a lot of pet food research. We think the scientific standards should be as high as possible. But no government agency funds pet food research; it’s mostly done by pet food companies with a vested interest in the outcome. And pet food companies won’t risk funding studies that might show no difference between one brand and another.

BARK: Do you have ethical concerns about using animals in feeding trials?

Nestle: We worried a lot about this question and consulted several animal ethicists. We were reassured when they all agreed that research is okay to do when it respects the animals. Whenever possible, they’d like feeding studies to be conducted in the dogs’ homes. But the dogs should always be treated well, allowed to move around and played with regularly. They want the studies to be relatively noninvasive and cause no harm. The dogs should be adopted into good homes. Beyond that, the experiments need to be top-quality science, carefully designed and closely monitored. Mal visited one pet food research facility that met these conditions. We assume that was why the company let him see it. Most others wouldn’t let us get near their facilities.

In Feed Your Pet Right, we go into the research issues, we hope entertainingly. We also discuss the nutrition training of veterinarians, which we view as a problem because so much of it is funded by pet-food companies. We think dogs, cats and their owners deserve better.

BARK: Both of you have recommended that pet owners contact pet food manufacturers to get information about how their product is made and what it contains. But as so many of us learned during the recalls, manufacturers don’t always know where each ingredient comes from. People who did call were put on hold, hung up on or given incorrect information—innocently or not—as well as given partial information or “official corporate statements” that didn’t answer their questions. Add to that the fact pet food labels aren’t comprehensible to most people. So how do we make a decision about commercial foods?

Nestle: It’s not easy. But we saw plenty of companies—Castor & Pollux and Natural Balance, for example—going to a lot of trouble to make what they were doing transparent, have their products tested, source their ingredients and post this information on their websites. All pet food companies need to be hearing from pet owners who care about these issues.

BARK: It sounds like you consider consumer contacts as a form of training for the pet food companies rather than something that will result in useful information for the pet owner.

Nestle: Yes. The question is whether you believe what the companies say. What else can you do? No government agency is checking. The FDA is up to its ears in contaminated peanut butter and pistachios, and pet food is way down on its priority list. We need some public uproar. The FDA only does what Congress tells it to. Pet owners need to be in close touch with their congressional representatives.

BARK: Given the high percentage of people who have pets—including, presumably, congressional representatives—it’s interesting that so many people don’t seem to understand what an enormous consumer issue this is.

Nestle: That’s because it’s “just pets.” We hear that all the time when we talk about what we’re writing. Even my friends say, “I haven’t read Pet Food Politics. Why would I read a book about pet food?” or “Why are you wasting your time writing about dogs and cats?” I didn’t think it was a waste of time at all. What affects the pet food supply affects the human food supply, and vice versa. And people are very emotionally involved with their pets. We see this as a big plus.

BARK: Can you give our readers a taste of what to expect when Feed Your Pet Right comes out next year?

Nestle: Mostly we tried to satisfy our curiosity. We wanted to know what ancestral wolves and cats ate and how they differed from modern dogs and cats. We wondered what pets ate before commercial pet food existed, so we went back to the earliest written records we could find. When did the pet food industry start? What did it look like in the past and what does it look like now? How is it regulated? What kinds of foods are on the market? How do you read their labels? What are different kinds of diets—commercial, home-cooked, raw, kosher, vegetarian—and how do they work? We also wanted to find out about related issues, like how veterinarians learn about nutrition and how ethicists view feeding experiments on dogs and cats. Our concluding chapter has recommendations for the FDA, manufacturers, veterinarians and pet owners about what they all need to be doing to improve the situation.

BARK: You’re typically very even-handed in your discussion of these issues. How do you think the different stakeholders—pet owners, veterinarians, pet food companies—are going to react to the book?

Nestle: We suspect that what you call our even-handedness will catch us in the middle on lots of issues. Although we ended up believing that dogs can be fed successfully in many different ways, we have plenty of critical things to say about the industry and veterinary nutrition training.

BARK: How so?

Nestle: We think veterinarians need to be taught more about nutrition, and by experts who don’t work for pet food companies. Mal surveyed veterinary schools to find out whether they were worried about the conflicts of interest caused by pet food company involvement. Most weren’t. They should be. The veterinary school at Cornell is covered with posters from pet food companies.

Nesheim: Right. And our students get free pet food from pet food companies.

Nestle: The entire system works just like drug company involvement in medical schools. Pet food companies provide free food and swag to students, write the major nutrition textbooks, and sponsor students and professors. And veterinary practices sell pet food. We think all this creates conflicts of interest that deserve some critical attention.

Plenty of evidence supports the idea that drug companies influence prescription practices. Why would pet food be any different? Veterinarians don’t have to know anything about nutrition because pet foods are “complete and balanced.” All they have to say is “Buy this brand.” That’s why Feed Your Pet Right isn’t so much about what to feed dogs or cats as it is about how to think about how to feed them. It’s a mixture of What to Eat and Food Politics for pets.

Nesheim: We also talk about how the veterinary profession thinks cooking for your pet is the worst thing in the world to do. After the melamine recalls, a veterinary group put out a statement saying that people should be careful about cooking for their own pets, because after all, pet food companies hire PhD nutritionists to do this. [Laughter]

Nestle: We laughed when we read Hills’ book about clinical nutrition for pets. It’s a really good book, but the chapter on pet feeding goes on and on about how it’s too dangerous to cook for pets. But then it gives completely simple, generic recipes for complete-and-balanced diets for dogs and cats. The recipes are so easy that anyone could follow them.

BARK: Would you make food for your pets?

Nestle: Oh, probably not. I hardly ever make food for myself.

Nesheim: I grew up on a farm and we fed our pets from the table. We didn’t buy pet food—we fed our pets pretty much what we ate.

BARK: How’d they do on that kind of diet?

Nesheim: They did just fine. We had very healthy, well-adjusted animals. We talk about this quite a bit in our book. How you decide to feed your pet depends a lot on your own value system. You can accommodate the nutritional needs of your pet in a variety of ways—commercial foods, home cooking, raw foods, or some combination. What you do depends on the amount of time you’re willing to spend, your value system and the kind of a life you want your pets to have. Fortunately, there are lots of good choices.